I was attempting to install a low flow aerator on what I thought was a normal sink (Price Pfister ball faucet, single lever. When it wouldn't unscrew easily we tried a wrench. Turns out it isn't a threaded assembly: there is a hole in it that the copper pipe for water enters the assembly. I am afraid we have broken a soldered connection, because I can't see how it is watertight, and we may have bent the pipe a bit to one side, as we can't get the assembly back in. Before I spend a lot on a plumber, any idea if I can fix this myself? I've tried to figure out the sink model but can't find any diagrams and such on the Price-Pfister site--they all show normal aerators.